Magnetic recording head having longitudinally spaced offset arrays

ABSTRACT

An apparatus according to one embodiment includes a head having at least two modules, each of the modules having an array of transducers and at least one servo transducer. An axis of each array is defined between opposite ends thereof. The axes of the arrays are oriented about parallel to each other. The axes of the arrays are spaced from one another in an intended direction of tape travel thereacross. The array of a first of the modules is offset from the array of a second of the modules in a first direction parallel to the axis of the array of the second module. All of the transducers of the first module are positioned on a first side of an imaginary line oriented in the intended direction of tape travel, wherein all of the transducers of the second module are positioned on a second side of the imaginary line.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to a magnetic head and systemimplementing the same, where the head includes two offset transducerarrays oriented parallel to each other, longitudinally and opposinglyoffset from one another so that the two arrays do not overlap the samedata tracks when reading and/or writing.

In magnetic storage systems, data is read from and written onto magneticrecording media utilizing magnetic transducers. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, magnetic tape is moved over the surface of thetape head at high speed. Usually the tape head is designed to minimizethe spacing between the head and the tape. The spacing between themagnetic head and the magnetic tape is crucial so that the recordinggaps of the transducers, which are the source of the magnetic recordingflux, are in near contact with the tape to effect writing sharptransitions, and so that the read element is in near contact with thetape to provide effective coupling of the magnetic field from the tapeto the read element.

The quantity of data stored on a magnetic tape may be increased byincreasing the number of data tracks across the tape. More tracks aremade possible by reducing feature sizes of the readers and writers, suchas by using thin-film fabrication techniques and MR sensors. However,for various reasons, the feature sizes of readers and writers cannot bearbitrarily reduced, and so factors such as lateral tape motiontransients and tape lateral expansion and contraction (e.g.,perpendicular to the intended direction of tape travel) must be balancedwith reader/writer sizes that provide acceptable written tracks andreadback signals. An issue limiting areal density is misregistrationcaused by tape lateral expansion and contraction. Tape dimensionalinstability (TDI) occurs when tape width varies by up to about 0.1% dueto expansion and contraction caused by changes in humidity, tapetension, temperature, aging etc. Tilting, pivoting and/or rotating (usedinterchangeably herein as equivalent terms) of transducer arrays cancompensate for misregistration due to TDI and keep the transducersaligned with tracks on the tape.

Inevitably, the desire to increase the rate at which data can berecorded to and read from a tape drive storage system to match theincreasing processor rate of computers has led to increasing the numberof readers and/or writers a single tape head module to up to, forexample, 64 in a single array and all operating concurrently. However, asingle array of 64 transducers in the same or smaller span than aprevious array design limits the amount of adjustable space betweenchannels in order to address TDI. Furthermore, the cables required pertape span for an array of 64 readers and/or writers may push the limitsof flex circuit design and fabrication processing capabilities.Moreover, cables for servicing 64 readers and/or writers presents asignificant problem in terms of congestion that may interfere withactive track following, and may increase cross talk potential betweenthe write channels or between write and read channels. As the tapecapacity increases over generations, managing increasing numbers ofreader and/or writer transducers and associated cabling requirementspresents significant challenges and is a limiting factor for growingareal density.

BRIEF SUMMARY

An apparatus according to one embodiment includes a head having at leasttwo modules, each of the modules having an array of transducers and atleast one servo transducer. An axis of each array is defined betweenopposite ends thereof. The axes of the arrays are oriented aboutparallel to each other. The axes of the arrays are spaced from oneanother in an intended direction of tape travel thereacross. The arrayof a first of the modules is offset from the array of a second of themodules in a first direction parallel to the axis of the array of thesecond module. All of the transducers of the first module are positionedon a first side of an imaginary line oriented in the intended directionof tape travel, wherein all of the transducers of the second module arepositioned on a second side of the imaginary line.

An apparatus according to another embodiment includes a head having atleast three modules, each of the modules having an array of transducersand at least one servo transducer. An axis of each array is definedbetween opposite ends thereof. The axes of the arrays are oriented aboutparallel to each other. The axes of the arrays are spaced from oneanother in an intended direction of tape travel thereacross. The arrayof a first of the modules is offset from the array of a second of themodules in a first direction parallel to the axis of the array of thesecond module. The array of the second of the modules is offset from thearray of a third of the modules in a first direction parallel to theaxis of the array of the third module. All of the transducers of thefirst module are positioned on a first side of an imaginary lineoriented in the intended direction of tape travel, wherein all of thetransducers of the second module are positioned on a second side of theimaginary line. All of the transducers of the second module arepositioned on a first side of a second imaginary line oriented in theintended direction of tape travel, wherein all of the transducers of thethird module are positioned on a second side of the second imaginaryline.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIGS. 8A-8C are partial top-down representational views of one module ofa magnetic tape head according to one embodiment.

FIGS. 9A-9B are partial top-down representational views of one set ofmodules of a magnetic tape head according to one embodiment.

FIG. 9C illustrates calculation parameters usable to determine the tiltto align a set of two separate longitudinally offset modules accordingto one embodiment.

FIG. 9D is a partial top-down representation view of one set of modulesof a magnetic tape head according to one embodiment.

FIG. 9E is a partial top-down representation view of one set of modulesof a magnetic tape head according to one embodiment.

FIG. 9F is a partial top-down representation view of one set of modulesof a magnetic tape head according to one embodiment.

FIG. 10 is a partial top-down representational view of a magnetic headwith three sets of modules according to one embodiment.

FIG. 11 illustrates a method for determining an array offset to aligntwo separate longitudinally offset modules according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems, as well as operation and/or component partsthereof. In some embodiments, a head includes at least two separatemodules, each module having for example half the number of requiredactive transducers in an array. The modules are arranged to enablefilling or reading a tape in which data is organized in databands, andmay be further arranged to enable compensating for tape dimensionalchanges.

In one general embodiment, an apparatus includes a head having at leasttwo modules, each of the modules having an array of write transducers.An axis of each array is defined between opposite ends thereof. The axesof the arrays are oriented about parallel to each other. The axes of thearrays are spaced from one another in an intended direction of tapetravel thereacross. The array of a first of the modules is offset fromthe array of a second of the modules in a first direction parallel tothe axis of the array of the second module such that the writetransducers of the first module and the write transducers of the secondmodule are positioned to fill a contiguous data band with written tracksin multiple passes. All of the write transducers of the first module arepositioned on a first side of an imaginary line oriented in the intendeddirection of tape travel, wherein all of the write transducers of thesecond module are positioned on a second side of the imaginary line.

In another general embodiment, an apparatus a head having at least twomodules, each of the modules having an array of read transducers and atleast one servo transducer. An axis of each array is defined betweenopposite ends thereof. The axes of the arrays are oriented aboutparallel to each other. The axes of the arrays are spaced from oneanother in an intended direction of tape travel thereacross. The arrayof a first of the modules is offset from the array of a second of themodules in a first direction parallel to the axis of the array of thesecond module such that the read transducers of the first module and theread transducers of the second module are positioned to read acontiguous data band of written tracks in multiple passes. All of theread transducers of the first module are positioned on a first side ofan imaginary line oriented in the intended direction of tape travel,wherein all of the read transducers are positioned on a second side ofthe imaginary line.

In yet another general embodiment, a drive-implemented method includesdetermining a desired array offset as presented to the tape for arraysof transducers of a head for reading and/or writing to a magnetic tape.Such head may be of a type noted above. The head is rotated to achievethe desired array alignment as presented to the tape.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may operate under logicknown in the art, as well as any logic disclosed herein. The controller128 may be coupled to a memory 136 of any known type, which may storeinstructions executable by the controller 128. Moreover, the controller128 may be configured and/or programmable to perform or control some orall of the methodology presented herein. Thus, the controller may beconsidered configured to perform various operations by way of logicprogrammed into a chip; software, firmware, or other instructions beingavailable to a processor; etc. and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (integral or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some embodiments, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreembodiments, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or other device.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 5 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B made of the same orsimilar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 22 data bands, e.g., with 8data bands and 9 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2B depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2B, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complimentarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write head 214 and the readers, exemplified by the read head 216,are aligned parallel to a direction of travel of a tape mediumthereacross to form an R/W pair, exemplified by the R/W pair 222.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to an intended direction of tape travel thereacross.However, the pairs may also be aligned diagonally, etc. Servo readers212 are positioned on the outside of the array of R/W pairs, thefunction of which is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write while-write capability by activating thewriter of the leading module and reader of the trailing module alignedwith the writer of the leading module parallel to the intended directionof tape travel relative thereto. When a module 224, 226 of a piggybackhead 200 is constructed, layers are formed in the gap 218 created abovean electrically conductive substrate 204A (partially shown), e.g., ofAlTiC, in generally the following order for the R/W pairs 222: aninsulating layer 236, a first shield 232 typically of an iron alloy suchas NiFe (—), CZT or Al-Fe-Si (Sendust), a sensor 234 for sensing a datatrack on a magnetic medium, a second shield 238 typically of anickel-iron alloy (e.g., ˜80/20 at % NiFe, also known as permalloy),first and second writer pole tips 228, 230, and a coil (not shown). Thesensor may be of any known type, including those based on MR, GMR, AMR,tunneling magnetoresistance (TMR), etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further embodiments, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹(δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.5° to about 1.1° , though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ may be set slightly less on theside of the module 304 receiving the tape (leading edge) than the innerwrap angle α₃ on the trailing edge, as the tape 315 rides above thetrailing module 306. This difference is generally beneficial as asmaller α₃ tends to oppose what has heretofore been a steeper exitingeffective wrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is25-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to an intended direction of tape travel over the respectivemodule. This enables positioning the modules closer together. One way toproduce shorter closures 334, 336 is to lap the standard ceramicclosures of the second module 304 an additional amount. Another way isto plate or deposit thin film closures above the elements during thinfilm processing. For example, a thin film closure of a hard materialsuch as Sendust or nickel-iron alloy (e.g., 45/55) can be formed on themodule.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan standard LTO tape head spacing. The open space between the modules302, 304, 306 can still be set to approximately 0.5 to 0.6 mm, which insome embodiments is ideal for stabilizing tape motion over the secondmodule 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures will force a widergap-to-gap separation. Therefore, a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same pitch as current 16 channel piggyback LTOmodules, or alternatively the connections on the module may beorgan-keyboarded for a 50% reduction in cable span. Over-under, writingpair unshielded cables can be used for the writers, which may haveintegrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head can bemaintained or even reduced relative to heads of previous generations. Inother embodiments, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads.

Data track density may be increased by compensating for variation of thetape lateral expansion and contraction using methods of tilting,pivoting and/or rotating (used interchangeably herein, said terms beingequivalents) of the transducer arrays to keep the transducers alignedwith tracks on the tape. FIGS. 8A-8C illustrate representational viewsof the effects of orienting a module having transducer arrays. It shouldbe noted that the angles of orientation illustrated in FIGS. 8A-8C arean exaggeration (e.g., larger than would typically be observed), and arein no way intended to limit the invention.

Referring to FIG. 8A, the module 800 is shown relative to the tape 802,where the tape has a nominal width. As illustrated, the module 800 isoriented at an angle θ_(nom) such that the transducers 804 are favorablyaligned with the data tracks 806 on the tape 802. However, when the tape802 experiences tape lateral contraction and/or expansion, the datatracks 806 on the tape contract and/or expand as well. As a result, thetransducers on the module are no longer favorably aligned with the datatracks 806 on the tape 802.

In FIG. 8B, the tape 802 has experienced tape lateral contraction.Therefore, in a manner exemplified by FIG. 8B, the transducers 804 onthe module 800 of FIG. 8B would no longer be favorably aligned with thedata tracks 806 on the tape 802 if no adjustment were made. Therefore,referring again to FIG. 8B, the angle of orientation >θ_(nom) of themodule 800 is further positioned in order to compensate for tape lateralcontraction at an angle greater than θ_(nom). By increasing the angleθ_(nom) the effective width w₂ of the array of transducers decreasesfrom the effective width w₁ illustrated in FIG. 8A. This also translatesto a reduction in the effective pitch between the transducers, therebyrealigning the transducers along the contracted data tracks 806 on thetape 802 as shown in FIG. 8B.

On the other hand, when the tape experiences tape lateral expansion, thedata tracks on the tape expand as well. As a result, the transducers onthe module would no longer be favorably aligned with the data tracks onthe tape if no adjustments were made. With reference to FIG. 8C, thetape 802 has experienced tape lateral expansion. Therefore, referringagain to FIG. 8C, the angle of orientation <θ_(nom) of the module 800 isreduced to an angle less than θ_(nom) in order to compensate for thetape lateral expansion. By decreasing the angle of orientation <θ_(nom)the effective width W₃ of the array of transducers 804 increases fromthe effective width w₁ illustrated in FIG. 8A. Moreover, reducing theeffective width of the array of transducers 804 also causes theeffective pitch between the transducers to be reduced, therebyrealigning the transducers along the data tracks 806 on the tape 802.

Currently in computer technology, it desirable to increase the rate atwhich data can be recorded to and read from a tape drive storage systemto match the increasing processor rate of computers. Contemplatedapproaches to increasing I/O capacity included increasing the number ofreaders and/or writers a single tape head module to up to, for example,64 in a single array. However, a single array of 64 transducers may havelimited adjustable space between channels in order to address tapedimensional instability. Furthermore, the cables required per tape spanfor an array of 64 readers and/or writers may push the limits of flexcircuit fabrication processing capabilities. Moreover, large, bulky,congested cables can interfere with active track following due to theincreased stiffness of larger cables, thereby resulting in possibledegradation of bit error rate and signal to noise ratio during readback. Attempts to reduce the size of a cable by moving traces closertogether were found to result in crosstalk between write channels, whichaffected writing, which in turn consequently resulted in furtherdegradation of bit error rate and signal to noise ratio during readback.

Thus, it would be desirable to develop a tape drive system that utilizesa small amount of rotation to maintain alignment of arrays of 64 or morereaders and/or writers to compensate for tape dimensional instabilitywhile relieving the cable congestion associated with these transducers.In conventional heads, adjusting rotation or tilting the head at anominal angle of at least 0.2° to 1° or more in order to compensate fortape lateral expansion and/or contraction may result in data timingdelays in the tilted array. Moreover, the increased cable congestionserving 64 or more writer transducers of an array that result in crosstalk between pairs of writers may not be solved with a tilt or rotationof the head.

Various embodiments described and/or suggested herein overcome theforegoing challenges of conventional products, where the tape drivesystem includes at least two offset transducer arrays oriented parallelto each other, and longitudinally and opposingly offset from one anotherso that the two arrays do not overlap the same data tracks when readingand/or writing. The modules may be arranged to enable substantiallyfilling a tape in which data is organized in data bands. Furthermore,the at least two modules may be aligned to enable compensating for tapedimensional changes e.g., by centering each array over its respectiveportion of the data band rather than performing the conventionalsubstantial tilting to create a pronounced change in transducer pitch aspresented to tape. Thus, by so aligning the arrays, potentialmisregistration between outermost transducers and existing tracks isreduced by approximately two times.

In a preferred embodiment, magnetic tape systems may have two or moreseparate modules, such that each module may have a portion of the arrayof required transducers for a given read or write operation such thatthe transducers of the arrays are positioned to read or write acontiguous data band in multiple passes. For example, for a head with 64transducers, each module may have 32 transducers in each array,typically in a straight row. The two separate modules may be spacedapart in direction of tape motion and vertically offset generallyperpendicular to the direction of tape motion such that the arrays donot overlap the same data tracks when reading and/or writing. Asmentioned above, the foregoing conventional challenges may be overcome,e.g., by splitting the number of transducers into smaller arrays onseparate modules and offsetting the smaller arrays. In some embodiments,the given modules may be rotated relative to orthogonal to the directionof tape travel thereover, e.g., in a plane parallel to the upper surfaceof the tape to adjust the alignment of the arrays as presented to thetape.

Providing a system that allows for increased numbers of transducers tooperate simultaneously, avoids the problems inherent with larger cables,and optionally may be configured for compensating for tape lateralexpansion and/or contraction. Various embodiments enable better signalto noise ratio (SNR), and/or higher capacity per unit area of the media.

FIGS. 9A-D depict an apparatus 900 having two, for example, 32-channelmodules in which the two 32 channel arrays together create a 64 channelarray that may fit a data band, in accordance with one embodiment. Ofcourse, a larger or smaller number of channels may be present in eacharray various embodiments. As an option, the present apparatus 900 maybe implemented in conjunction with features from any other embodimentlisted herein, such as those described with reference to the other FIGS.Of course, however, apparatus 900 and others presented herein may beused in various applications and/or in permutations which may or may notbe specifically described in the illustrative embodiments listed herein.Further, the apparatus 900 presented herein may be used in any desiredenvironment.

FIGS. 9A-9E depict various embodiments having transducers 914 inmultiple arrays. The transducers in each array may be read transducers,write transducers, or both read and write transducers, e.g., piggybacktransducer pairs. To provide a context for the reader, the descriptionof FIGS. 9A-9E will refer to write transducers. This is done by way ofexample only, and it should be understood that the transducers 914referred to herein may be read transducers.

Referring to FIG. 9A, the apparatus 900 includes a magnetic head 950that may have at least two modules 902, 904, each of the modules mayhave an array 906, 908 of write transducers such that an axis 912, 913of each array (FIG. 9B) is defined between opposite ends thereof, andthe axes 912, 913 of the arrays may be oriented about parallel to eachother as well as may be spaced from one another in an intended directionof tape travel 920 thereacross. Furthermore, the array 906 of the writetransducers 914 of the module 902 may be offset from the array 908 ofwrite transducers 914 of a second of the modules 904 in a firstdirection parallel to the axis 913 of the array 908 of a second module904 such that the write transducers of the first module 902 and thewrite transducers of the second module 904 may be positioned to fill acontiguous data band 806 with written tracks in multiple passes. In thepreferred embodiment, all of the write transducers of the first module902 may be positioned on a first side of an imaginary line 910 orientedin the intended direction of tape travel 920, where all of the writetransducers of the second module 904 may be positioned on a second sideof the imaginary line 910 that is opposite the side of the first module902.

The modules 902, 904 may be nominally arranged such that the arrays areoriented perpendicular to the direction of tape travel 920. See, e.g.,the expanded detail of FIG. 9A.

The modules 902, 904 may be identically formed, where one module ismerely rotated relative to the other. In this approach, the transducersin each module may be evenly distributed, confined to one side of theimaginary line 910, or primarily located on one side of the imaginaryline 910. In further approaches, the transducers in an array may beeither symmetrically or asymmetrically positioned on the respectivemodule. Where more transducers are present than will be used, only thosetransducers to be used may be connected to a cable.

As depicted in FIG. 9A, a mechanism 916 may be employed for orientingthe modules 902, 904 to control the offset between the arrays aspresented to a tape 802 with the controller 918 being configured tocontrol the mechanism 916 for orienting the modules 902, 904. Theorientation of the modules 902, 904 may be adjusted for following tapeskew. In some approaches, the controller 918 may be configured tocompensate for TDI.

For example, in a preferred embodiment, the angle of the axes 912, 913of the arrays relative to a line oriented perpendicular to the directionof tape travel 920 may be adjusted to position the center of eachrespective array over its portion of the data band on tape. Theadjustment is slight, and not in the range of the significantly greatertilting, rotating and/or pivoting is used for TDI compensation bychanging the transducer pitch presented to tape, which is described inmore detail above with respect to FIGS. 8A-8C. The tilting shown inFIGS. 8A-8C is intended to compensate for tape lateral expansion andcontraction within an array of transducers of a module. In sharpcontrast, various embodiments use slight corrective tilting that adjuststhe position of each array separately to move the center of each arrayas closely as possible to the center of the respective portion of thedata band. Because the pitch of the transducers as presented to tapedoes not significantly change, some misregistration may occur along theouter ends of each array. Nonetheless, the effect of TDS is reduced by afactor of two where two arrays are present. Therefore, the extent ofmisregistration would be minimal. Where three arrays are present, themisregistration is reduced three-fold.

Moreover, this procedure proceeds counterintuitively by providing moretilt in response to detecting tape lateral expansion, and less tilt inresponse to detecting tape lateral contraction. For example, the arrayoffset as presented to tape is increased when an expanded tape conditionis detected. Rotating the head to increase the array offset actuallyreduces the transducer pitch presented to tape but by a negligibly smallamount. However, centering each array over its portion of the data bandon tape may provide improved TDI compensation in spite of the veryslight misregistration caused by the smaller transducer pitch aspresented to tape. Such misregistration may be compensated for by thechannel processing circuitry.

According another embodiment illustrated in FIG. 9B, the writetransducers of each array may have a same pitch Pi along the axis of therespective array, where the pitch Pi is the same in both arrays 906,908. The pitch Pi of the write transducers 914 of both arrays 906, 908together as presented to the tape 802 may be about the same when theaxes 912, 913 of the arrays 906, 908 are oriented at a nominal angle φ,e.g., as fixed in the drive, set using a mechanism and/or controller(see 916, 918 of FIG. 9A) relative to a line 922 orthogonal to theintended direction of tape travel 920.

According to an exemplary embodiment as depicted in FIG. 9C, which is inno way intended to limit the invention, the modules of the tape head 950may be aligned according to any of the embodiments described herein,e.g. by determining the angle of orientation φ of tilt to align themodules to maintain the alignment of the longitudinally spaced offsetmodules according to the boundary of the write area of each module. Asshown, when the axes of the arrays are orthogonal to the direction oftape motion, a clockwise rotation of the modules increases the offset ofthe arrays relative to each other in the direction orthogonal to thedirection of tape motion, while rotation in the counterclockwisedirection reduces the offset.

According to one embodiment, the distance D between the axes 912, 913 ofthe arrays 906, 908 and the initial overlap O of boundary B of the writeareas of the write transducers in the array 908 may be used to calculatethe angle of orientation φ of the modules 902 and 904 to align themodules to each other. As illustrated, the angle of orientation withrespect to the boundary of the write area of each module and thedistance between the arrays of transducers of the modules in a directionparallel to their axes 912, 913, which may be calculated using Equation1.tan(φ)=O/D  Equation 1

Equation 1 can be rewritten into Equation 2.φ=arc tan (O/D) Equation 2

Other known methods of calculating and/or assigning the angle oforientation φ, distance D between the arrays of any of the modules, andthe initial boundary offset O of the write area of each module may beused in other embodiments.

In other embodiments, the module offset at manufacturing assembly may begreater than a format requires, in which case a rotation toward normalto the direction of tape travel is needed to achieve proper alignmentbetween arrays and tape.

The head modules may preferably be skew actuated to correct for tapeskew.

According to a preferred embodiment, and with continued reference toFIG. 9B, the axes 912, 913 of the arrays 906, 908 may be oriented at anominal angle φ that is greater than 0.01°, relative to a line 922oriented perpendicular to the intended direction of tape travel 920.However, according to various other embodiments, the angle φ ispreferably between about 0.005° and about 0.035°, and ideally betweenabout 0.015° and about 0.025°, but could be higher or lower. The smalltilt angle φ for alignment of the offset arrays may not have asignificant effect on the pitch between the writer transducers aspresented to tape. Thus, the timing differences within an array andbetween arrays may be easily corrected in code or may be negligible.

With continued reference to FIG. 9B, the distance D between the axes912, 913 of the arrays 906, 908 in the intended direction of tape travel920 may be at least about 0.01 mm, preferably at least about 0.25 mm toabout 1.0 mm, and in some approaches up to about 1.5 mm.

The angle φ at which the axes 912, 913 of the arrays 906, 908 areoriented may be adjustable, and in some approaches continuously orperiodically adjusted, based at least in part on any desirable factor.In one approach as shown in FIG. 9C, the selection of the angularorientation of the axes 912, 913 may be made based on obtaining properalignment of the arrays 906, 908 relative to each other to acquire theproper offset apparent to tape between the innermost transducer 915 ofeach array. This adjusting of angle φ should not be confused with themore exaggerated tilting, rotating and/or pivoting for TDI compensationby changing the transducer pitch within an array presented to tape,which is described in more detail above with respect to FIGS. 8A-8C.

In a preferred embodiment, adjusting of angle φ is slight, and not inthe range of the more exaggerated tilting, rotating and/or pivoting forTDI compensation by changing the transducer pitch presented to tape,which is described in more detail above with respect to FIGS. 8A-8C.Rather, the following method proceeds counterintuitively by providingmore tilt in response to detecting tape lateral expansion, and less tiltin response to detecting tape lateral contraction. For example, thearray offset as presented to tape is increased when an expanded tapecondition is detected. Rotating the head to increase the array offsetactually very slightly reduces the transducer pitch presented to tape.However, centering each array over its portion of the data band on tapegives a two-times reduction in misregistration that would result fromTDI.

Now referring to FIG. 11, a flowchart of a method 1100 for introducing atilt for a head of any type described herein to set a transducer arrayalignment as presented to tape, is shown according to one embodiment.The method 1100 may be used to create any of the various embodimentsdepicted in FIGS. 1-10, among others, in various embodiments. Of course,more or less operations than those specifically described in FIG. 11 maybe included in method 1100, as would be understood by one of skill inthe art upon reading the present descriptions. Each of the steps of themethod 1100 may be performed using known techniques according to theteachings herein.

Referring to step 1102 of FIG. 11, the method may include determining adesired offset for the transducer arrays. In one embodiment, the desiredoffset may be determined based on the state of the tape. An exemplarymechanism for establishing the proper offset is to use the timinginterval read by two servo readers to determine the state of the tape,e.g., contracted, expanded or nominal. Although a preferred mode is touse servo data, this is not absolutely required. Thus, it may bedesirable to determine the state of the tape, e.g., by incorporating anyof the embodiments described and/or suggested herein and/or knownprocesses, when determining the desired offset. However, according toother embodiments, the offset may be determined using any embodimentdescribed and/or suggested herein, or combinations thereof. Note thatthe transducers in the first and second arrays may be of a same type,e.g., all readers or all writers, in some approaches.

Referring to step 1104 of FIG. 11, the head may be rotated to achievethe desired array alignment as presented to the tape. Note that tapetension may also be used in conjunction with method 1100 to correct forat least some TDI.

In further embodiments, any of the steps of the method described abovemay be performed concurrently. For example, in one embodiment the properarray offset may be based on data signals. One way to implement this isby first setting the array offset at a nominal value by selecting anominal angle, and then adjusting the orientation thereof to obtain abetter readback quality across the read channels. The quality may bedetermined for example by finding the lowest error rate, best signal tonoise level, etc.

Referring again to FIG. 9B, the transducers 914 of each array 906, 908may have a same pitch P₁ along the axis 912, 913 of the respective array906, 908, such that the pitch Pi may be the same in both arrays, and thepitch P₁ of the transducers 914 of both arrays 906, 908 together aspresented to the tape may be about the same when the axes 912, 913 ofthe arrays 906, 908 are rotated to achieve the desired pitch aspresented to the tape.

With continued reference to FIG. 9B, where the head is pivoted to setits angle of orientation, the center of pivot of the head 950 may extendthrough the module of the first or second array, or some pointtherebetween, with the head pivoting about an axis approximatelyorthogonal to the plane of the tape surface using conventionaltechniques used by individuals skilled in the art. For example, thepivot point may align with an intersection of the center of the firstarray 906 and the axis 912 of the first array. Moreover, the position ofthe modules may be adjusted using the actuator as necessary to positionthe active arrays over the appropriate tracks, e.g., based on servo orother signals.

In other embodiments, linear actuation generally parallel to the axis ofthe associated array may be used to adjust the offset.

Depending on the embodiment, the center-to-center pitch of all datatracks for a given tape may be specified by the format of the tape, e.g.legacy format, current format. Moreover, according to variousembodiments, the format of the tape may specify reading, writing and/orservo following to access data stored in the data tracks of a tape,using a non-tilted head, e.g., having a transducer pitch that aboutmatches the center to center pitch of the data tracks specified in theformat. A format may also specify servo frames aligned with each otherin a direction perpendicular to the intended direction of tape travel,for a non-tilted head. In one approach, the pitch of the writetransducers of the arrays as presented to a tape about matches the pitchof sub data bands specified in the data format the head is designed tocomply with.

As an option, the system may continue or periodically monitor theappropriate signals and adjust the orientation. Adjustments can beperformed any time, such as during an initialization period prior toreading or writing user data, during readback or writing operations, tocompensate for tape skew, etc.

As depicted in FIG. 9D, a mechanism 916 may be employed for orientingthe modules 902, 904 to control the array offset presented to a tape 802with the controller 918 being configured to control the mechanism 916for orienting the modules 902, 904 based on a state of expansion of thetape 802. Furthermore, the controller 918 may also enable writing oftransitions that are readable by a non-tilted head compatible with theformat. In some embodiments, the system 900 may include a drivemechanism for passing a magnetic medium 802 over the head 950 as well asa controller 918 electrically coupled to the head.

According to some embodiments, the dimensional conditions of the tapewhen the tape was written may be retrieved e.g., from a database,cartridge memory, etc., and the TDI compensating orientation may be setbased thereon to about match the transducer pitch of the currentoperation to that of the previous operation.

In various embodiments, additional logic, computer code, commands, etc.,or combinations thereof, may be used to control the mechanism 916 foradjusting the orientation of the modules based on alignment of the twooffset modules to each other and/or skew of the tape. Moreover, any ofthe embodiments described and/or suggested herein may be combined withvarious functional methods, depending on the desired embodiment.

As illustrated in FIG. 9D, the separate cables 924, 926 for the writetransducers of each separate offset array 906, 908 may minimizecrosstalk between cables in the head 950 compared to having all, forexample, 64 channels in a single module, and thus requiring a singlecable for all 64 channels. For example, an exemplary embodimentdemonstrates that 0.3 to 1.0 mm distance D (as depicted in FIG. 9B)between axes 912, 913 of the separate offset modules 902, 904 mayprovide sufficient space in the cables to minimize writer-to-writercrosstalk in the cables.

Although the magnetic head 950 illustrated in FIGS. 9A-9D includes onlytwo modules 902, 904, according to other embodiments, a system mayinclude more than two modules, e.g., three modules, at least threemodules (e.g., see FIG. 10), multiple modules, etc., depending on thedesired embodiment.

Furthermore, according to a preferred embodiment, each module 902, 904may include at least one servo transducer (e.g., see 212 of FIG. 2C),and possibly two or three servo transducers. For example, FIG. 9Adepicts two servo transducers 960 on each module. FIG. 9E depicts anembodiment 952 having three servo transducers 960 on each module.

To assemble any of the embodiments described above, the separate offsetmodules may be fixed together, e.g. coupled together using conventionalu-beam assembly. Those skilled in the art, armed with the presentteachings, will appreciate that other known methods of manufacturingsuch heads may be adapted for use in constructing such heads.

Again, while the foregoing description of FIGS. 9A-9D discuss thetransducers in terms of being write transducers, various embodiments mayhave read transducers instead of write transducers. Such configurationsmay otherwise be identical, with the exception of the transducer type,and electronics particular to the transducer type, e.g., read channelsfor read transducers.

An apparatus may include any number of modules e.g., at least two, atleast three, at least four, a plurality, etc. depending on the desiredembodiment. In an exemplary embodiment which is in no way intended tolimit the invention, the outer modules of each set may be configured forwriting, and the inner modules may be configured for reading (as shownin FIGS. 5, 6 and 7).

FIG. 9F depicts an embodiment having three modules 902, 904, 980, eachhaving an array 906, 908, 982 of transducers that together are arrangedto read from and/or write to a contiguous data band in multiple passes.In a 64 channel write configuration, for example, the inner array mayhave 22 active writers and each outer array may have 21 active writers.Of course, any conceivable arrangement of transducers may be used on themultiple modules, in various embodiments.

In a further approach, the offset transducer arrays may be fabricated ona single module. For example, the distance D between the axes of thearrays could be smaller than in embodiments using two separate modules,and in some approaches, perhaps down to about 50 nm.

FIGS. 10 depicts an apparatus 1000 having a tape head with several setsof longitudinally offset arrays in accordance with one embodiment. As anoption, the present apparatus 1000 may be implemented in conjunctionwith features from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, such anapparatus 1000 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 1000 presented herein may be used in any desired environment.

As illustrated in FIG. 10, the apparatus 1000 may serve as awrite-read-write (WRW) device where the transducers 1014 and 1064 of theouter modules 1002, 1004 and 1052, 1054 may be writers and thetransducers 1044 of the inner modules 1032, 1034 may be readers. In oneillustrative use case, the writers on the outer module of one set maywrite while the readers of an inner module of the second set may readback the just-written written track. In another illustrative use case,the writers on the outer module of one set may write while the readersof an inner module of the same set may read back the just-written track.

As alluded to above, in another embodiment, the apparatus 1000 (FIG. 10)may serve as a read-write-read (RWR) device if the first and secondmodules 1002, 1004 and the fifth and sixth modules 1052, 1054 aredesigned for at least data reading and optionally not for data writing,while the third and fourth modules 1032, 1034 are designed for at leastdata writing and optionally not for data reading. However, this is in noway meant to limit the invention; according to various otherembodiments, a third, fourth, fifth, etc. module may be positioned withany orientation relative to other modules of the apparatus, depending onthe desired embodiment.

In configurations having multiple pairs of modules, any suitablemechanism may be used to ensure that the various pairs remain over theintended portion of the data band during skew compensation, etc. Forexample, each module pair may be independently acuatable.

It will be clear that the various features of the foregoing systems,apparatuses and/or methodologies may be combined in any way, creating aplurality of combinations from the descriptions presented above.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Moreover, a system according to various embodiments may include aprocessor and logic integrated with and/or executable by the processor,the logic being configured to perform one or more of the process stepsrecited herein. By integrated with, what is meant is that the processorhas logic embedded therewith as hardware logic, such as an applicationspecific integrated circuit (ASIC), a FPGA, etc. By executable by theprocessor, what is meant is that the logic is hardware logic; softwarelogic such as firmware, part of an operating system, part of anapplication program; etc., or some combination of hardware and softwarelogic that is accessible by the processor and configured to cause theprocessor to perform some functionality upon execution by the processor.Software logic may be stored on local and/or remote memory of any memorytype, as known in the art. Any processor known in the art may be used,such as a software processor module and/or a hardware processor such asan ASIC, a FPGA, a central processing unit (CPU), an integrated circuit(IC), a graphics processing unit (GPU), etc.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above. It will be furtherappreciated that embodiments of the present invention may be provided inthe form of a service deployed on behalf of a customer to offer serviceon demand.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

What is claimed is:
 1. An apparatus, comprising: a head having at least two modules, each of the modules having an array of transducers and at least one servo transducer, wherein an axis of each array is defined between opposite ends thereof, wherein the axes of the arrays are oriented about parallel to each other, wherein the axes of the arrays are spaced from one another in an intended direction of tape travel thereacross, wherein the array of a first of the modules is offset from the array of a second of the modules in a first direction parallel to the axis of the array of the second module, and wherein all of the transducers of the first module are positioned on a first side of an imaginary line oriented in the intended direction of tape travel, wherein all of the transducers of the second module are positioned on a second side of the imaginary line.
 2. An apparatus as recited in claim 1, wherein the pitch of the transducers of the arrays as presented to a tape about matches the pitch of sub data bands specified in a data format the head is designed to comply with.
 3. An apparatus as recited in claim 1, wherein the transducers of each array have a same pitch along the axis of the respective array, wherein the pitch is the same in both arrays, wherein the pitch of the transducers of each array as presented to the tape is about the same when the axes of the arrays are oriented at a nominal angle relative to a line orthogonal to the intended direction of tape travel.
 4. An apparatus as recited in claim 3, wherein the nominal angle is between about 0.005 and about 0.035 degrees.
 5. An apparatus as recited in claim 1, wherein a distance between the axes of the arrays in the intended direction of tape travel is at least about 0.25 mm.
 6. An apparatus as recited in claim 1, comprising a mechanism for orienting the modules to control an offset of the arrays of the transducers as presented to a tape; and a controller configured to control the mechanism for orienting the modules.
 7. An apparatus as recited in claim 6, wherein the controller is configured to control the mechanism for orienting the modules to increase a distance of the arrays from the imaginary line when the tape is in a relatively expanded state, wherein the controller is configured to control the mechanism for orienting the modules to decrease a distance of the arrays from the imaginary line when the tape is in a relatively contracted state.
 8. An apparatus as recited in claim 1, wherein each module has three servo readers.
 9. An apparatus as recited in claim 1, comprising: a drive mechanism for passing a magnetic medium over the head; and a controller electrically coupled to the head.
 10. An apparatus, comprising: a head having at least three modules, each of the modules having an array of transducers and at least one servo transducer, wherein an axis of each array is defined between opposite ends thereof, wherein the axes of the arrays are oriented about parallel to each other, wherein the axes of the arrays are spaced from one another in an intended direction of tape travel thereacross, wherein the array of a first of the modules is offset from the array of a second of the modules in a first direction parallel to the axis of the array of the second module, wherein the array of the second of the modules is offset from the array of a third of the modules in a first direction parallel to the axis of the array of the third module, wherein all of the transducers of the first module are positioned on a first side of an imaginary line oriented in the intended direction of tape travel, wherein all of the transducers of the second module are positioned on a second side of the imaginary line, and wherein all of the transducers of the second module are positioned on a first side of a second imaginary line oriented in the intended direction of tape travel, wherein all of the transducers of the third module are positioned on a second side of the second imaginary line.
 11. An apparatus as recited in claim 10, wherein the pitch of the transducers of the arrays as presented to a tape about matches the pitch of sub data bands specified in a data format the head is designed to comply with.
 12. An apparatus as recited in claim 10, wherein the transducers of each array have a same pitch along the axis of the associated array, wherein the pitch is the same in both arrays, wherein the pitch of the transducers in each array of transducers together as presented to the tape is about the same when the axes of the arrays are oriented at a nominal angle relative to a line orthogonal to the intended direction of tape travel.
 13. An apparatus as recited in claim 12, wherein the nominal angle is between about 0.005 and about 0.035 degrees.
 14. An apparatus as recited in claim 10, wherein a distance between the axes of the arrays in the intended direction of tape travel is at least about 0.25 mm.
 15. An apparatus as recited in claim 10, comprising a mechanism for orienting the modules to control an offset of the arrays of the transducers as presented to a tape; and a controller configured to control the mechanism for orienting the modules based on a state of expansion of the tape.
 16. An apparatus as recited in claim 15, wherein the controller is configured to control the mechanism for orienting the first and second modules to increase a distance of the arrays of the first and second module from the imaginary line when the tape is in a relatively expanded state, wherein the controller is configured to control the mechanism for orienting the second and third modules to increase a distance of the arrays of the second and third module from the second imaginary line when the tape is in a relatively expanded state, wherein the controller is configured to control the mechanism for orienting the first and second modules to decrease a distance of the arrays of the first and second modules from the imaginary line when the tape is in a relatively contracted state, and wherein the controller is configured to control the mechanism for orienting the second and third modules to decrease a distance of the arrays of the second and third modules from the second imaginary line when the tape is in a relatively contracted state.
 17. An apparatus as recited in claim 10, wherein each module has three servo readers.
 18. An apparatus as recited in claim 10, comprising: a drive mechanism for passing a magnetic medium over the head; and a controller electrically coupled to the head. 